Field of the Invention
The present invention relates to an image forming apparatus using an electrophotographic method, such as a laser beam printer (LBP), a copying machine, a facsimile machine, and the like.
Description of the Related Art
A frame structure of an image forming apparatus that uses two side plates facing each other across a photosensitive member is known, as discussed in Japanese Patent Application Laid-Open No. 2009-128506. In an image forming apparatus having the frame structure including two side plates, an image forming unit including a photosensitive member and a stacking unit (sheet feeding cassette) that is attachable to and detachable from a main body of the image forming apparatus and on which sheets to be conveyed to the image forming unit are stacked are provided between the two side plates.
Meanwhile, the distance between the two side plates is generally determined by a length of the widest object among members provided between the two side plates. For example, in a case of a configuration in which a tray supporting a cartridge is provided and the tray can be inserted and removed as discussed in Japanese Patent Application Laid-Open No. 2009-128506, the tray and a tray insertion/removal mechanism need to be provided between the two side plates. However, the smallest width of the sheet feeding cassette is not always the same as the smallest width of the tray and the tray insertion/removal mechanism. Thus, if the distance between the two side plates is set to allow the tray, the tray insertion/removal mechanism, and the sheet feeding cassette to fit in the space between the two side plates, an empty space is formed in a portion between the two side plates and the tray and the tray insertion/removal mechanism or in a portion between the two side plates and the sheet feeding cassette. The empty space causes an excessive increase in the volume of the image forming apparatus, whereby it becomes difficult to reduce the size of the image forming apparatus.